] Willoughby chose money over his love for Marianne. Edward chose honor over his love for Elinor. The motives and impetus behind both men is what makes the difference, and allows Elinor to look past her own pain and forgive Edward. Willoughby's actions are unforgiveably selfish.

I think what makes me wonder about this situation is not so much about who deserves forgiveness or not, but whether or not it brings peace of mind to the person to be able to forgive. It is true that what Willoughby has done is more 'unforgiveable' than Edward's actions. But still--Elinor knew that it brought her comfort and peace of mind to be able to be able to acquit him in her own mind.

Marianne's wish to do this in her thoughts of Willoughby is also because she must feel much to blame for what happened, and so that respect she is even more in need of peace of mind than Elinor.